4.3 LX Mercrusier runs rough and won?t Idle

ksoren1779

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Joined
May 6, 2011
Messages
3
1996 Bayliner 1850CS Capri LS Bowrider
4.3 Liter LX Alpha One
180HP; 6 Cyl; 4 Stroke
Serial Number: 0F751121
Carburetor: 4BBL Weber 9600s 1355 (95137)
Ignition: 4.3LX/V6 Alpha One Balanced Shaft/Thunderbolt IV

FYI: I have only been running it with MUFFS
My boat hasn't been started for 2-years. I had purged fuel tank before so all fuel is clean/new. New spark plugs with gap set to specifications. Fuel filter checked and looks good. Distributor Cap removed; looked clean.

Problem:

Engine will start and run OK at about 1500 RPMS or higher but will not idle. Higher the RPMS the better it runs.

The fuel tank Vent (that vents out the rear of boat) is not clogged
Removed fuel lines; all hard lines from Carb to fuel pump looked good
Removed and replaced soft line from tank/anti-siphon valve to pump
Did not replace anti-siphon valve; looked clean and seemed to work
Tried to remove Pick-up tube but afraid to damage (Fiberglass Tank). I did insert a fitting with hose attached was able to blow through without restriction

I have played with Air and fuel adjustments a little with little improvement
Any assistance will be greatly appreciated.

Kevin
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,148
Re: 4.3 LX Mercrusier runs rough and won?t Idle

1996 Bayliner 1850CS Capri LS Bowrider
4.3 Liter LX Alpha One
180HP; 6 Cyl; 4 Stroke
Serial Number: 0F751121
Carburetor: 4BBL Weber 9600s 1355 (95137)
Ignition: 4.3LX/V6 Alpha One Balanced Shaft/Thunderbolt IV

FYI: I have only been running it with MUFFS
My boat hasn't been started for 2-years. I had purged fuel tank before so all fuel is clean/new. New spark plugs with gap set to specifications. Fuel filter checked and looks good. Distributor Cap removed; looked clean.

Problem:

Engine will start and run OK at about 1500 RPMS or higher but will not idle. Higher the RPMS the better it runs.

The fuel tank Vent (that vents out the rear of boat) is not clogged
Removed fuel lines; all hard lines from Carb to fuel pump looked good
Removed and replaced soft line from tank/anti-siphon valve to pump
Did not replace anti-siphon valve; looked clean and seemed to work
Tried to remove Pick-up tube but afraid to damage (Fiberglass Tank). I did insert a fitting with hose attached was able to blow through without restriction

I have played with Air and fuel adjustments a little with little improvement

Any assistance will be greatly appreciated.

Kevin

Ayuh,... Rebuild yer Carb,...

The idle circuits are boogered up....
 
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